Illustration of triangle
- 1 equilateral
- 2 acute
- 3 obtuse
- 4 scalene
- 5 isosceles
- 6 right triangle
triangle
noun
tri·an·gle
ˈtrī-ˌaŋ-gəl 
1
: a polygon having three sides compare spherical triangle
2
a
: a percussion instrument consisting of a rod of steel bent into the form of a triangle open at one angle and sounded by striking with a small metal rod
b
: a drafting instrument consisting of a thin flat right-angled triangle of wood or plastic with acute angles of 45 degrees or of 30 degrees and 60 degrees
3
: a situation in which one member of a couple is involved in a love affair with a third person
Examples of triangle in a Sentence
She cut the sandwiches into triangles.
Recent Examples on the Web
The film follows Lucy, a young, ambitious New York City matchmaker who finds herself in a love triangle with one of her clients, an investment banker (Pascal), and her ex (Evans), a scrappy, struggling actor.
—
Saman Shafiq, USA Today, 6 Nov. 2025
His legacy is alive and well in the nightclubs of Recife, the capital city, where couples dance to forró’s distinctive ringing of triangles and humming zabumba drum until the early hours.
—Carolina Abbott Galvão, Travel + Leisure, 5 Nov. 2025
The triangle of home, school, and work can make or break daily life, which is why one Bay Area couple was willing to overlook a few flaws in a Lafayette house that sat perfectly between their son’s school in Oakland and the wife’s job in Walnut Creek.
—Vaishnavi Nayel Talawadekar, Architectural Digest, 4 Nov. 2025
The district is shaped like a triangle in south Charlotte and includes neighborhoods such as Eastover, Myers Park, South Park, Providence and Carmel.
—Charlotte Observer, 2 Nov. 2025
See All Example Sentences for triangle
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Saman Shafiq, USA Today, 6 Nov. 2025
His legacy is alive and well in the nightclubs of Recife, the capital city, where couples dance to forró’s distinctive ringing of triangles and humming zabumba drum until the early hours.
—Carolina Abbott Galvão, Travel + Leisure, 5 Nov. 2025
The triangle of home, school, and work can make or break daily life, which is why one Bay Area couple was willing to overlook a few flaws in a Lafayette house that sat perfectly between their son’s school in Oakland and the wife’s job in Walnut Creek.
—Vaishnavi Nayel Talawadekar, Architectural Digest, 4 Nov. 2025
The district is shaped like a triangle in south Charlotte and includes neighborhoods such as Eastover, Myers Park, South Park, Providence and Carmel.
—Charlotte Observer, 2 Nov. 2025
See All Example Sentences for triangle
Cite this Entry
“Triangle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/triangle. Accessed 8 Nov. 2025.
Copy CitationKids Definition
triangle
noun
tri·an·gle
ˈtrī-ˌaŋ-gəl
1
: a figure that has three sides and three angles : a polygon that has three sides
2
: a percussion instrument made of a steel rod bent into a triangle open at one corner which is played by striking with a metal rod
3
: a drafting instrument consisting of a thin flat right-angled triangle
Medical Definition
triangle
noun
tri·an·gle
ˈtrī-ˌaŋ-gəl
: a three-sided region or space and especially an anatomical one see anterior triangle, carotid triangle, femoral triangle, posterior triangle, suboccipital triangle
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